Identifying Rocks and Minerals

Week 4-Earth Science

What is a mineral?

• solid
• naturally occurring
• inorganic
• characteristic chemical composition
• crystal form

e.g. quartz

Why care about minerals?

Cells=building blocks of life

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Minerals=building blocks of rocks

Traits to identify minerals

• Color
• Streak
• Luster
• Hardness
• Density
• Crystal Structure/Cleavage
• Other physical properties

(fluorescent, magnetic, reacts with acid)

NHMU at the University of Utah

From Minerals to Rocks

3 main types of rocks

Sedimentary

Igneous

Metamorphic

Sedimentary Rocks

1. Clastic: small pieces glued together (sandstone)

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• Chemical: when rock forms from dissolved minerals (limestone, cave formations)

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• Organic: formed from the remains of once-living stuff (coal)

Stratification

“layering” of sedimentary rocks

Sedimentary Rocks

Igneous Rocks

formed from cooling lava or magma

How fast lava/magma cools determines crystal size and rock type

Really fast: No crystals (obsidian)

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Fast: small crystals (basalt)

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Slow: large crystals (granite)

Igneous Rocks

Metamorphic Rocks

Take any other rock and apply heat and pressure

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Occur near lava plumes or across large regions.

How much heat and pressure determines what rock you end up with…

• Shale (sedimentary rock)
• Slate
• Phylite
• Schist
• Gneiss

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Metamorphic Rocks

Forces that drive the rock cycle

1. Erosion and Weathering
2. Heat and Pressure
3. Melting and Cooling
4. Uplift and Burying

Photo Homework Idea

By the End of This Week…

• I can explain the characteristics of a mineral.
• I'll be able to sort different rocks and minerals by looking at their physical features.
• I can use a guide to figure out what type of mineral or rock I might be looking at.